PHP 下载远程文件类(支持断点续传)

PHP 下载远程文件类,支持断点续传下载，代码内含有具体的调用说明。程序主要是使用 HTTP 协议下载文件，HTTP1.1协议必须指定文档结束后关闭链接,否则读取文档时无法使用feof判断结束，可以有两种使用方法，具体请下载查看源码。

<?php
    /**
     * 下载远程文件类支持断点续传
     */
    class HttpDownload {
        private $m_url = "";
        private $m_urlpath = "";
        private $m_scheme = "http";
        private $m_host = "";
        private $m_port = "80";
        private $m_user = "";
        private $m_pass = "";
        private $m_path = "/";
        private $m_query = "";
        private $m_fp = "";
        private $m_error = "";
        private $m_httphead = "" ;
        private $m_html = "";
      
        /**
         * 初始化
         */
        public function PrivateInit($url){
            $urls = "";
            $urls = @parse_url($url);
            $this->m_url = $url;
            if(is_array($urls)) {
                $this->m_host = $urls["host"];
                if(!empty($urls["scheme"])) $this->m_scheme = $urls["scheme"];
                if(!empty($urls["user"])) $this->m_user = $urls["user"];
                if(!empty($urls["pass"])) $this->m_pass = $urls["pass"];
                if(!empty($urls["port"])) $this->m_port = $urls["port"];
                if(!empty($urls["path"])) $this->m_path = $urls["path"];
                $this->m_urlpath = $this->m_path;
                if(!empty($urls["query"])) {
                    $this->m_query = $urls["query"];
                    $this->m_urlpath .= "?".$this->m_query;
                }
            }
        }
      
        /**
        * 打开指定网址
        */
        function OpenUrl($url) {
            #重设各参数
            $this->m_url = "";
            $this->m_urlpath = "";
            $this->m_scheme = "http";
            $this->m_host = "";
            $this->m_port = "80";
            $this->m_user = "";
            $this->m_pass = "";
            $this->m_path = "/";
            $this->m_query = "";
            $this->m_error = "";
            $this->m_httphead = "" ;
            $this->m_html = "";
            $this->Close();
            #初始化系统
            $this->PrivateInit($url);
            $this->PrivateStartSession();
        }
     
        /**
        * 获得某操作错误的原因
        */
        public function printError() {
            echo "错误信息：".$this->m_error;
            echo "具体返回头：<br>";
            foreach($this->m_httphead as $k=>$v) {
                echo "$k => $v <br>\r\n";
            }
        }
      
        /**
        * 判别用Get方法发送的头的应答结果是否正确
        */
        public function IsGetOK() {
            if( preg_match('#^2#',$this->GetHead("http-state")) ) {
                return true;
            } else {
                $this->m_error .= $this->GetHead("http-state")." - ".$this->GetHead("http-describe")."<br>";
                return false;
            }
        }
         
        /**
        * 看看返回的网页是否是text类型
        */
        public function IsText() {
            if (preg_match('#^2#',$this->GetHead("http-state")) && preg_match('#^text#i',$this->GetHead("content-type"))) {
                return true;
            } else {
                $this->m_error .= "内容为非文本类型<br>";
                return false;
            }
        }
        /**
        * 判断返回的网页是否是特定的类型
        */
        public function IsContentType($ctype) {
            if (preg_match('#^2#',$this->GetHead("http-state")) && $this->GetHead("content-type") == strtolower($ctype)) {
                return true;
            } else {
                $this->m_error .= "类型不对 ".$this->GetHead("content-type")."<br>";
                return false;
            }
        }
         
        /**
        * 用 HTTP 协议下载文件
        */
        public function SaveToBin($savefilename) {
            if (!$this->IsGetOK()) return false;
            if (@feof($this->m_fp)) {
                $this->m_error = "连接已经关闭！";
                return false;
            }
            $fp = fopen($savefilename,"w") or die("写入文件 $savefilename 失败！");
            while (!feof($this->m_fp)) {
                @fwrite($fp,fgets($this->m_fp,256));
            }
            @fclose($this->m_fp);
            return true;
        }
         
        /**
        * 保存网页内容为 Text 文件
        */
        public function SaveToText($savefilename) {
            if ($this->IsText()) {
                $this->SaveBinFile($savefilename);
            } else {
                return "";
            }
        }
         
        /**
        * 用 HTTP 协议获得一个网页的内容
        */
        public function GetHtml() {
            if (!$this->IsText()) return "";
            if ($this->m_html!="") return $this->m_html;
            if (!$this->m_fp||@feof($this->m_fp)) return "";
            while(!feof($this->m_fp)) {
                $this->m_html .= fgets($this->m_fp,256);
            }
            @fclose($this->m_fp);
            return $this->m_html;
        }
         
        /**
        * 开始 HTTP 会话
        */
        public function PrivateStartSession() {
            if (!$this->PrivateOpenHost()) {
                $this->m_error .= "打开远程主机出错!";
                return false;
            }
            if ($this->GetHead("http-edition")=="HTTP/1.1") {
                $httpv = "HTTP/1.1";
            } else {
                $httpv = "HTTP/1.0";
            }
            fputs($this->m_fp,"GET ".$this->m_urlpath." $httpv\r\n");
            fputs($this->m_fp,"Host: ".$this->m_host."\r\n");
            fputs($this->m_fp,"Accept: */*\r\n");
            fputs($this->m_fp,"User-Agent: Mozilla/4.0+(compatible;+MSIE+6.0;+Windows+NT+5.2)\r\n");
            #HTTP1.1协议必须指定文档结束后关闭链接,否则读取文档时无法使用feof判断结束
            if ($httpv=="HTTP/1.1") {
                fputs($this->m_fp,"Connection: Close\r\n\r\n");
            } else {
                fputs($this->m_fp,"\r\n");
            }
            $httpstas = fgets($this->m_fp,256);
            $httpstas = explode(' ',$httpstas);
            $this->m_httphead["http-edition"] = trim($httpstas[0]);
            $this->m_httphead["http-state"] = trim($httpstas[1]);
            $this->m_httphead["http-describe"] = "";
            for ($i=2;$i<count($httpstas);$i++) {
                $this->m_httphead["http-describe"] .= " ".trim($httpstas[$i]);
            }
            while (!feof($this->m_fp)) {
                $line = str_replace("\"","",trim(fgets($this->m_fp,256)));
                if($line == "") break;
                if (preg_match('#:#',$line)) {
                    $lines = explode(':',$line);
                    $this->m_httphead[strtolower(trim($lines[0]))] = trim($lines[1]);
                }
            }
        }
         
        /**
        * 获得一个Http头的值
        */
        public function GetHead($headname) {
            $headname = strtolower($headname);
            if (isset($this->m_httphead[$headname])) {
                return $this->m_httphead[$headname];
            } else {
                return "";
            }
        }
         
        /**
        * 打开连接
        */
        public function PrivateOpenHost() {
            if ($this->m_host=="") return false;
            $this->m_fp = @fsockopen($this->m_host, $this->m_port, $errno, $errstr,10);
            if (!$this->m_fp){
                $this->m_error = $errstr;
                return false;
            } else {
                return true;
            }
        }
         
        /**
        * 关闭连接
        */
        public function Close(){
            @fclose($this->m_fp);
        }
    }
    
    #两种使用方法，分别如下：
    
    #打开网页
    $httpdown = new HttpDownload();
    $httpdown->OpenUrl("http://www.google.com.hk");
    echo $httpdown->GetHtml();
    $httpdown->Close();
    
    
    #下载文件
    $file = new HttpDownload(); # 实例化类
    $file->OpenUrl("http://www.ti.com.cn/cn/lit/an/rust020/rust020.pdf"); # 远程文件地址
    $file->SaveToBin("rust020.pdf"); # 保存路径及文件名
    $file->Close(); # 释放资源
 ?>

来源：http://www.open-open.com/lib/view/open1333676622436.html